When a bore is created by drilling equipment, a casing is typically inserted into the well to reinforce the sides and to provide a secure conduit for equipment and debris. The interior wall of the casing must be kept free of dirt and debris in order to ensure the smooth passage of equipment and exiting debris. After a well is completed, tools must be inserted to check various aspects of the well. These tools often include a brushing tool to clean the inside surface of the casing and remove debris. Because of the harsh environment in which these brushes must operate, the bristle material must be tough and resilient, yet efficient at removing and evacuating debris. These brushes typically include numerous welds to retain the various brush components. In use, these welds have a high failure rate, which causes the brush to fail, potentially damaging the well bore.
Existing designs typically use either steel or nylon brush elements. Common designs include plug-type or row-type inserts. Plug-type inserts generally feature cylindrically-shaped bristle modules that may be inserted into a base piece mounted on a shaft extending through the well bore; see, for example, U.S. Pat. No. 3,176,772. The inserts may be arranged in a spiral pattern around the shaft circumference. Row-type inserts commonly feature several rows of bristles on a base piece that may be mounted to a shaft extending through the well bore. The rows are generally arranged in an angled parallel arrangement around the circumference of the shaft. These designs, however, suffer from several deficiencies. First, the relatively small number of bristles in these designs decreases the brushes' cleaning ability, and the relatively large space between inserts reduces the brushes' ability to evacuate loose debris. Second, the use of multiple bristle inserts increases the time and labor required to replace the bristles. Third, existing designs commonly use carbon steel or nylon bristles, which do not withstand the harsh environment inside the well bore casing for very long. Finally, existing designs are constructed by bonding or crimping individual bristles to the base piece, resulting in the loss of bristles as the brush operates.
A need, therefore, exists for a well bore casing brush that efficiently removes and evacuates debris, is easy to replace, and holds up to the conditions inside the well bore casing.